BEDFORD — It plugs into an electrical socket like an alarm clock, a coffee maker or a toaster. But its job isn't to wake people up. It is to slow them down.

The portable box, which is about as big as a speed limit sign, registers how fast motorists are traveling here.

"Any time we get a request to monitor traffic on a street, we can put it up and have the results in a few days," Police Chief Greg Duber said.

The device counts the number of vehicles on a road, their speed and the time of day. When motorists spot the device, they can see the speed limit, their speed, or no numbers at all, depending on how it is set up.

"If there is a problem with speeders on the street, we can identify the specific time periods to put our patrol cars there to use radar and issue citations," Duber said.

"To use an officer specifically for radar or to monitor the traffic flow is a waste of resources," he said. "It's just taking an officer out of commission."